It is a paradox that has frustrated researchers for decades: Egypt preserves bodies, through natural desiccation and artificial mummification, better than almost any other ancient environment.

It preserves the physical form of ancient Egyptians in extraordinary detail.

But the warm temperatures that permit physical preservation are hostile to the molecular preservation of DNA.

Svante Pääbo, reflecting on his early failed attempts, has described the Egyptian climate as one of the most challenging environments for ancient DNA work.

The heat is, in molecular terms, destructive in ways that the cold environments of Siberia or the Arctic are not.

In permafrost, DNA can survive for tens of thousands of years in readable condition.